Automatic slack adjuster for railway cars



2 SHEETS-SHEET 1 A. W. DONOP AUTOMATIC SLACK ADJUSTER FOR RAILWAY CARS INVENT-UR. Bygd W 1707290.

Aug. l2, 1952 Filed oct. 22, 1949 Aug. l2, 1952 A. w. DoNoP AUTOMATIC SLACK ADJUSTER FOR RAILWAY CARS 2 SHEETS-SHEET 2 illl'lll Wagggs-nnen atenteci Aug. 1:2,

UNITED STATES PATENT QFFICE ases-,62s- AuToMA'ric snack ADJUs'rR son.

RAILWAY vCARS l August W. Donop, Chicago, Ill., assignor to Ajax- Consolidated Company, Chicago, Ill., a corporation of Illinois Application Uctoberf, 1949, Sierial No. 122,941

n Y 7 Claims. (Cl. 18S-498) This invention relates, generaily, to brake rigging for railway cars, and it has particular relation to automatic slack adjusters therefor.

Among the objects of this invention are: to provide for taking up slack in the brake rigging of a railway car automatically when there is a predetermined amount of slack therein; to control the operation` of the slack adjusting mechanism as a vfunction of thedisplacement of the piston in the air brake cylinder by means of which the brakes are applied; to change the position of the fulcrum of the floating iulcrurn lever in the brake rigging to take up or adjust theslack therein; to accomplish this by winding a chain connected to the fulcrum point or the lever around a drum; to prevent reverse rotation of the drum; to rotate the drum forwardly in small increments to take up or adjust the slack; to rotate theldrum by a pawl operated forwardly by a spring and retracted by a diaphragm type piston in a slack adjusting air cylinder connected to the air brake cylinder so that air pressure is applied to the diaphragm when the piston in the air brake cylinder moves to a predetermined position; and to prevent reverse movement of'vsaid pawl and drum should the means intended normally to prevent such reverse movement fail to function.

Other objects of this invention wilLin part, be

obvious and in part appear hereinafter.

This invention is disclosed in the yembodiment thereof shown in the accompanying drawings, and it comprises the features of construction, combination of elements and arrangement vof parts which will be exemplified in thereonstruction hereinafter set forth and the scope of the application of which will be indicated inthe appended claims.

For a more complete understanding of the nature and scope ofv this invention, reference can be had to the following detailed description,

taken together with the accompanying drawings,

Figure 5l is a view, similar to Figure 4, but showing the manner in which the drum on which the chain is wound is prevented from rotating in a reverse direction in the event that the holding pawl should fail to hold andffail to prevent the reverse rotation, as it is intended normally to do.

Referring now particularly to vFigure l of the drawings, it will be observed thatthe reference character i designates, generally, a conventional brake rigging which isV used `widely on railway cars. The brake rigging It includes brake beams II, I2, I3, and It which carrybrake shoes at their ends 4that are hung by links from the truck side frames..` This construction is well known to those skilled in thel art, and, accordingly, it is not further shown nor described herein. The brake beams II and I4 are pivoted on truck dead levers I5 and I6 Vthat are` pivoted to dead lever fulcrums or links I'i and i3. The fulcrums or links Il and I3 are pivoted to arms I9 and 2B that are carried by the truck side frames. It will be observed that the truck dead levers I5 and It are pivoted at 2l and 22 to the .fulcruins or links I1 and land that these pivot points are adjustable therealong. The purpose of these adjustmentsis to provideforY taking up slack manually in the brake rigging il) as the brake shoeswear.

The brake beams 4I2 and I3 are carried-by and pivoted on truck livelevers 24 and' 25 which are connected by ,bottom rods' and'tofthe truck dead levers .I5 and I6, respectively. The truck live levers E'liand L25 are connected 'to' top truck rods B and 3i through which the braking power is applied for moving the brake beams `I I, i2, I3, and it and the brake shoes carried-thereby toward the wheels for applying the brakes. The top truck rod Sii is .pinnedto a cylinder lever 32 while the top .truck rod 3l ispinned to a floating fulcrum lever` 33 whose fulcrum is indicated at 34 vand the vposition of .which may be adjustedby van automatic: slack adjuster, shown generally at 35, in which the present, invention is embodied.

The floating fulcrum lever 33 is connected intermediate its ends by Va cylinder rod 35 to t-he cylinder lever 32. The latter has a push rod 31 pivoted thereto, It Will be noted-that the. pushrod 3l has a-piston-SS atthe oppositeend ;which is slidable in an air brake cylinder 39. VWitliinthe `air lbrake cylinder 3Q there is a coil compression 3 duit 4| from a car air reservoir 42. The flow of air from the reservoir 42 to the cylinder 39 is controlled by a valve 43 in conventional manner.

The brakes also may be applied through a hand brake rod 44 by a hand brake mechanism that is indicated, generally, at 45. It will be noted that the hand brake rod 44 also is connected to the cylinder lever 32.

As indicated hereinbefore the present invention is directed particularly to the automatic slack adjuster 35 which is shown in more detail in Figures 2, 3 and 4 of the drawings. As there shown, the automatic slack adjuster 35 includes a support 48 which is arranged to lbe bolted or otherwise secured to the car body. The support 48 carries a frame, indicated generally at 49, having a slot 59, Figure 4, therein into which the fulcrum end of the floating fulcrum lever 33 projects.

The fulcrum end of the floating fulcrum lever 33 is secured by a pin 5| to a clevis 52 that is attached to one end of a exible inextensible member such as a chain 53. The other end of the chain 53 is connected by a pin 54 to a drum 55 and is arranged to be wound thereon so as to shift the position of the fulcrum point 34 of the floating fulcrum lever 33 and take up the slack in the brake rigging I8.

The drum 55 is mounted for rotation on a shaft 56 which extends through and is journaled in a pair of frame side members 51 which form a part of the frame 49. Formed integrally with the drum 55 is a holding ratchet wheel 58. A holding pawl 59 cooperates with the teeth of the holding ratchet wheel 58. The holding pawl 59 is rockably mounted on a shaft 60 which extends between and is carried by the frame side members 51. The end 6I of the holding pawl 59 opposite the toothed portion which engages the teeth of the holding ratchet wheel 58 constitutes a coun- -terweight and acts to bias the holding pawl 59 into engagement with the teeth of the holding ratchet wheel 58.

Also formed integrally with the drum 55 is a slack adjusting ratchet wheel 62. An operating pawl 63 is arranged to cooperate with the slack adjusting ratchet wheel 62 for rotating the same forwardly so as to wind the chain 53 on the drum 55 and take up the slack in the brake rigging l0. It will be noted in Figure 4 that the operating pawl 63 is pivoted at 64 on one arm 65 of a yoke that is indicated, generally, at 66. The yoke 66 is rockably mounted on a shaft 61 which extends between and is carried by the frame side members 51.

In order to rotate the slack adjusting ratchet wheel 62 forwardly by corresponding forward movement of the operating pawl 63, a coil compression spring 68 is employed. It will be noted in Figure 4 that one end of the spring 68 bears against a portion of the support 48 while its other end is arranged to act through a rod 69 having a ball shaped head 18 at its opposite end which interiits with a socket 1l in the arm 65. It will be understood that the spring 68 is compressed by means to be described and that, when the force applied to compress it is removed, it expands and moves the operating pawl 63 forwardly or to the right to effect a corresponding movement of the slack adjusting ratchet wheel 62.

' The yoke 66 also includes an arm 14 which is movable conjointly with the arm 65. The arm 14 L is pivoted at to a clevis 18 which may be threaded on one end of a push rod 11.

As shown more clearly in Figure 2 of the draw- 4 ings, the other end of the push rod 11 is arranged to be operated by a diaphragm type piston that is indicated, generally, yat 18. The diaphragm type piston 18 includes a head 19 which is connected directly to the left hand end of the push rod 11. A flexible diaphragm 88 interconnects the head 19 with a wall 8| of a slack adjusting air cylinder that is indicated, generally, at 82. A coil compression spring 83 is provided inside of the slack adjusting air cylinder 82 for returning the head 19 to the initial position shown in Figure 2. The spring 83 acts in the same direction as the coil compression spring 68 and, if desired, may be omitted.

The use of the diaphragm type piston 18 is important in the present construction. When it is employed there is no necessity for providing a lubricant in the slack adjusting air cylinder 82. Furthermore, since the diaphragm 89 has a relatively long life, substantially no maintenance of the diaphragm type piston 18 is required.

Air for operating the diaphragm type piston 18 is supplied through a conduit 84 which is connected at 85, Figure 1, to the air brake cylinder 39. It will be noted that the conduit 84 is connected to the air brake cylinder 39 at such a position, for example at a position where the piston 38 must move through a distance of seven inches, that the slack in the brake rigging I8 is taken up only after the amount thereof exceeds a predetermined value. Thus, as long as the slack in the brake rigging I6 is not sufficient to permitl the piston 38 to travel in applying the Vbrakes sufiiciently far to uncover the opening into the conduit 84, no air pressure is applied to the daphragm type piston 18 and no adjustment of the slack of the brake rigging I0 is made.

There is a remote possibility that the holding pawl 59 may not perform its intended function of preventing reverse rotation of the drum 55. Such action might occur in the event that the holding ratchet wheel 58 were coated with ice and the drum 55 were advanced one notch in taking up the slack in the brake rigging I0. In such case the ice in the next notch might prevent the holding pawl 59 from engaging with the next tooth on the holding ratchet wheel 58. It is important that the fulcrum point 34 of the floating fulcrum lever 33 .be held stationary when the brakes are applied for otherwise, it is not possible to apply them. If the drum 55 should not be prevented from rotating in a reverse direction by the holding pawl 59, when the valve 43 is opened in an attempt to apply the brakes, the drum 55 will be rotated in a reverse direction and will carry with it the operating pawl 63 and parts attached thereto. Since these parts are relatively light and weak, they cannot resist the reverse rotation of the drum 55 and, as a result, the brakes will not be applied since the fulcrum point 34 is not held stationary, and further the automatic slack adjuster 35 may be severely damaged or possibly substantially destroyed.

With a View to preventing the reverse rotation of the drum 55 under such conditions where the holding pawl 59 does not perform its intended function, the operating pawl 63 is provided with an inclined end surface 88 that is arranged to engage a transverse stop pin 89 which extends between and is carried by the frame side members 51. Now, if the holding pawl 59 fails to prevent reverse rotation of the drum 55, the operating pawl 63, which is biased by its weight into engagement with the slack adjusting ratchet wheel 62, moves rearwardly as the drum 55 is rotated in a reverse direction. However, such' 'movemnti limited by the engagement of the e'r'i'd surface 88 with the transverse stop pin 89. Notonly does'the pin 89 prevent further reverse rotation of the drm-n.55 but also, because of the inclined end surface 88, the operating pawl'63 is moved into wedging engagement with the slack adjusting ratchet wheel as indicated more clearly in Figure 5. Here the possible position of the holding pawl 59 is indicated which would permit the drum 55 to rotate in a reversedirection in the event that the transverse stop pin 89 were not provided.

In describing the operation of the present invention it will be assumed that the slack in the brake rigging ii) initially is adjusted by locating the fulcrum points 2l 4and 22 along the dead lever fulcrums I'l and i8. Preferably the adjustment is such that no part of the chain 53 is wound on the drum 55. This then permits of maximum automatic adjustment by the slack adjuster 35. As longas the piston 38 is not required to travel past the point 85 where the conduit 84 is connected to the air brake cylinder 39, no operation of the automatic slack adjuster `35 takes place. However, when the slack in the brake rigging-iii is such that the piston 38 is required to move in the air brake cylinder 39 so as to uncover the conduit S4, on the next application of air to the air brake cylinder 39, air will be supplied through thereon- `duit 84 to the slack adjusting air cylinder 82. ,The diaphragm type piston 'Iii will be moved to the right as Viewed in Figure 2 and, through the push rod ll, the yoke Et will be rocked in a counterclockwise direction. The operating pawl 63 vwill be moved rearwardly to engage the next tooth of the slack adjusting ratchet wheel 52 and the coil compression spring E8 Vwill be'oompressed correspondingly. During this interval the drum 55 is prevented from rotating in a reverse direction by the holding pawl 59.

No further action takes place until the air pressure is released and the brake rigging iii no longer applies the brakes. The release of air pressure from the slack adjusting air cylinder 82 permits the spring 5S to move the operating pawl 65 forwardly and to effect a corresponding forward rotation of the drum 55. This is permitted since the brakes are not applied and the fulcrum point 34 of the floating fulcrum lever'33 is not held stationary. The chain V53 is wound on the drum 55 a slight amount. The forward rotation of the drum 55 is permitted by `the holding pawl .5@ which, since it is biased by the counterweight action of the opposite end Giacts to engage the next tooth and prevents reverse frotation of the drum 55. In this manner .the slack in the brake rigging Hl is automatically adjusted 'in small increments and is maintained at a predetermined Value as will be understood readily.

Since certain changes can be made in the foregoing construction and different embodiments of the invention can be made without departing i from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

'What is claimed as new is: l

1.l An automatic slack adjuster for a fulcrum lever. such as theoating fulcrumleveigof a railway car brakerigging operated by a piston' in an air brake cylinder comprising, in combination, a rotatabledrum, a flexible yiriextensible member for connection at one end to the fulcrum point of s aid fulcrumlever andconnected at its other end to said drum for winding thereon on acca-ese forward rotation thereof to take 'up the lslack in said brake rigging, ratchet wheel means rotatable with said drum, an operating pawl cooperating with said ratchet wheel means, a stop member in the path of said operating pawl and adapted to be engaged thereby on rearward movement thereof beyond a predetermined position together with saidratchet wheel means to prevent further reverse movement thereof, a spring connected to said operating pawl for moving it to rotate said drum forwardly, a slack adjusting cylinder having a piston therein operatively connected to said spring, and a conduit from said slack adjusting air cylinder for connection to said air brake cylinder at a location where operating pressureis applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said piston in said slack a'djusting cylinder tensions said'spring and moves said operating pawl rearwardly to engage the next tooth of said ratchet wheel means, the redease of air pressure from said air brake cylinder and from said slack adjusting air cylinder permitting said spring to rotate said drum forwardly.

2. An automatic slack adjuster for a fulcrum lever, such as the floating fulcrum lever, of a railway car brake rigging operated by a piston in an air brake cylinder comprising, in combination, a rotatable drum, a chain for connection at one end to the fulcrum point of said fulcrum lever and connected at its other end to said drum for winding thereon on forward rotation thereof to take up the slack in said brake rigging, ratchet wheel means rotatable with said drum, a holding pawl biased into engagement with said ratchet wheel means and acting to prevent reverse rotation of said drum, an operating pawl cooperating with said ratchet wheel means, a stop member in the path of said operating pawl and adapted to be engaged thereby on failure of said holding pawl f to prevent reverse rotation of said drum whereby such reverse rotation is prevented, a spring connected to said operating pawl and acting to move it to rotate said drum forwardly, a slack adjusting cylinder having a piston therein operatively connected to said spring, and a conduit from said slack adjusting air cylinder for connection to said air brake cylinder at a location where operating pressure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position -in applying the brakes whereupon said piston in said slack adjusting Ycylinder tensions said spring and moves said operating pawl rearwardly to engage the next .tooth of said ratchet wheel means, the release of air pressure from said brake cylinder and from said slack adjusting air cylinder permitting said spring to rotate said drum forwardly.

3. An automatic slack adjuster for a fulcrum lever, such as the floating fulcrum lever, of a railway car brake rigging operated by a piston in an air brake cylinder comprising, in combination, a rotatable drum, a chain for connection at one end to the fulcrum point of said fulcrum lever and connected at its other end to said drum for winding thereon on forward rotation thereof to take up the slack in said brake rigging, ratchet wheel means rotatable with said drum, a holding pawl biased into engagement with said ratchet wheel means and acting to prevent reverse rotation of said drum, a rockably mounted member, an operating pawl pivoted to said member and biased into engagement with said ratchet wheel means', a

stop member in the path of said operating pawl and adapted to be engaged thereby on failure of said holding pawl to prevent reverse rotation of said drum whereby such reverse rotation is prevented, a spring connected to said member and acting to move said operating pawl so as to rotate said drum forwardly, a slack adjusting cylinder having a piston therein connected to said member, and a conduit from said slack adjusting air cylinder for connection to said air brake cylinder at a location where operating pressure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said piston in said slack adjusting cylinder rocks said member, tensions said spring and moves said operating pawl rearwardly to engage the next tooth of said ratchet wheel means, the release of air pressure from said air brake cylinder and from said slack adjusting air cylinder permitting said spring to rotate said drum forwardly.

4. An automatic slack adjuster for a fulcrum lever, such as the floating fulcrum lever, of a Yrailway car brake rigging operated by a piston in an air brake cylinder comprising, in combination, a rotatable drum, a chain for connection atlone end to the fulcrum point of said fulcrum lever and connected at its other end to said drum for Winding thereon on forward rotation thereof to take up the slack in said brake rigging, ratchet wheel means rotatable with said drum, a holding pawl biased into engagement with said holding ratchet wheel means and acting to prevent reverse rotation of said drum, a rockably mounted member, an operating pawl pivoted to said member and biased into engagement with said ratchet wheel means, a stop in the path of said operating pawl and adapted to be engaged thereby on failure of said holding pawl to prevent reverse rotation of said drum for holding said operating pawl in engagement with said ratchet wheel means and preventing further reverse rotation thereof, a spring connected to said member and acting to move said operating pawl so as to rotate said drum forwardly, a slack adjusting air cylinder having a piston therein connected to said member, and a conduit from said slack adjusting air cylinder for connection to said air brake cylinder at a location where operating pressure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said piston in said slack adjusting air cylinder rocks said member, tensions said spring and moves said operating pawl rearwardly to engage the next tooth of said ratchet wheel means, the release of air pressure from said air brake cylinder and from said slack adjusting air cylinder permitting said coil compression spring to rotate said drum forwardly.

5. An automatic slack adjuster for a fulcrum lever, such as the floating fulcrum lever, of a railway car brake rigging operated by a piston in an air brake cylinder comprising, in combination, a rotatable drum, a chain for connection at one end to the fulcrum point of said fulcrum lever and connected at its other end to said drum for winding thereon on forward rotation thereof to take up the slack in said brake rigging, ratchet wheel means rotatable with said drum, a holding pawl biased into engagement with said ratchet wheel means and acting to prevent reverse rotation of said drum, a rockably mounted member, an operating pawl having an inclined end surface pivoted to said member and biased into engagement with said ratchet wheel means, a transverse pin in the path of said end surface of said operating pawl and adapted to be engaged thereby on failure of said holding pawl to prevent reverse rotation of said drum for wedging said operating pawl into engagement with said ratchet wheel means and preventing further reverse rotation thereof, a spring connected to said member and acting to move said operating pawl so as to rotate said drum forwardly, a slack adjusting air cylinder having a piston therein connected to said member, and a conduit from said slack adjusting air cylinder for connection to said air brake cylinder at a location where operating pressure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said piston in said slack adjusting air cylinder rocks said member, tensions said spring and moves said operating pawl rearwardly to engage the next tooth of said ratchet wheel means, the release of air pressure from said air brake cylinder and from said slack adjusting air cylinder permitting said coil compression spring to rotate said drum forwardly.

6. An automatic slack adjuster for a fulcrum lever, such as the fioating fulcrum lever, of a railway car brake rigging operated by a piston in an air brake cylinder comprising, in combination, a rotatable drum, a chain for connection at one end to the fulcrum point of said fulcrum lever and connected at its other end to said drum for winding thereon on forward rotation thereof to take up the slack in said brake rigging, holding and slack adjusting ratchet wheels rotatable with said drum, a holding pawl biased into engagement with said holding ratchet wheel and. acting to prevent reverse rotation of said drum, a rockably mounted yoke, an operating pawl pivoted to one arm of said yoke and biased into engagement with said slack adjusting ratchet wheel, a stop in the path of said operating pawl and adapted to be engaged thereby on failure of said holding pawl to prevent reverse rotation of said drum for holding said operating pawl in engagement with said slack adjusting ratchet wheel and preventing further reverse rotation thereof, a coil compression spring connected to said arm and acting to move said operating pawl so as to rotate said drum forwardly, a slack adjusting air cylinder having a piston therein connected to the other arm of said yoke, and a conduit from said slack adjusting air cylinder for connection to said air brake cylinder at a location where operating pressure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said piston in said slack adjusting air cylinder rocks said yoke, compresses said spring and moves said operating pawl rearwardly to engage the next tooth of said slack adjusting ratchet wheel, the release of air pressure from said air bra-ke cylinder and from said slack adjusting air cylinder permitting said coil compression spring to rotate said drum forwardly.

7. An automatic slack adjuster for a fulcrum lever, such as the oating fulcrum lever, of a railway car brake rigging operated by a piston in an air brake cylinder comprising, in combination, a rotatable drum, a chain for connection at one end to the fulcrum point of said fulcrum lever and connected at its other end to said drum for winding thereon on forward rotation thereof to take up the slack in said brake rigging, holding and slack adjusting ratchet wheels rotatable with said drum, a holding pawl biased into engagernent with said holding ratchet wheel and acting to prevent reverse rotation of said drum, a rockably mounted yoke, an operating pawl having an inclined end surface pivoted to one arm of said yoke and biased into vengagement with said slack adjusting ratchet wheel, a transverse pin in the path of said end surface of said operating pawl and adapted to be engaged thereby on failure of said holding pawl to prevent r-everse rotation of said drum for wedging said operating pawl into engagement with said slack adjusting ratchet wheel and preventing further reverse rotation thereof, a coil compression spring connected to said arm and acting to move said op erating pawl so as to rotate said drum forwardly, a slack adjusting air cylinder having a diaphragm type piston therein connected to the other arm of said yoke, and a conduit from said slack ad-v justing air cylinder for connection to said air brake cylinder at a location where operating pres- 10 sure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said diaphragm type piston rocks said yoke, compresses said spring and moves said operating pawl rearwardly to engage the next tooth of said slack adjusting ratchet wheel, the release of air pressure from said air brake cylinder and from said slack adjusting air cylinder permitting said coil compression spring to rotate said drum forwardly.

AUGUST W. DONOP.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,407,628 Berry et al Feb. 21, 1922 2,097,533 Redford Nov. 2, 1937 2,433,139 Martin Dec. 23, 1947 

